English: Polyelectrolyte biopolymers tend towards linearity due to like-charge repulsive interactions on the backbone. DNA, for example, tends towards linearity due to repulsive interactions between the negative charges of its phosphodiester-linked backbone. Neutral biopolymers tend to fold and aggregate due to the lack of like-charge repulsive interactions. Folding is generally a favorable process in neutral biopolymers because it creates favorable intramolecular interactions. For example, proteins tend to fold because this produces favorable interactions between the dipole moments of the backbone, between complementary amino acid side chains, and the exchange of unfavorable hydrophilic-hydrophobic interactions for favorable hydrophobic-hydrophobic interactions of the protein core.